Liquid–liquid phase separation (LLPS), which results in the formation of highly concentrated droplets of biomolecules, is involved in various physiological phenomena. We have performed a label-free quantification of the concentration of a G-quadruplex-forming RNA and an RGG peptide in a single droplet using Raman microscopy. The concentration ratio of the RNA to the peptide within the droplet was found to maintain even when the prepared concentration ratio of these two species was varied. This result indicates that electrostatic interactions between the RNA and the peptide induced the droplet formation. It was also shown that the RNA maintains its G-quadruplex structure inside the droplets.

液-液相分离 (LLPS) 导致形成高度浓缩的生物分子液滴，涉及各种生理现象。我们使用拉曼显微镜对单个液滴中形成 G-四链体的 RNA 和 RGG 肽的浓度进行了无标记定量。发现液滴内 RNA 与肽的浓度比即使在这两种物质的制备浓度比发生变化时也能保持不变。该结果表明 RNA 和肽之间的静电相互作用诱导了液滴的形成。还表明，RNA 在液滴内保持其 G-四链体结构。